What if Caitlin Snow was The Flash?
by Alisha Winchester Collins
Summary: Written for Snowells Week: Day 2 - 'What if...'
1. Chapter 1

**This is one of my most cherished stories I've written in a while because the original idea didn't work out and I wasn't sure if I would end up writing anything at all but literally two nights before I had to post something, this new version came to me out of nowhere and it felt right! Hope you all enjoy this! ^_^**

* * *

 _"My name is Caitlin Snow, and I'm the fastest woman alive. When I was a teenager, I saw the man I loved killed by something impossible. His murder was never solved. Then an accident made me the impossible. To the outside world, I'm an ordinary bio-engineer, but secretly I use my speed to fight crime and find others like me. And one day I'll find who killed Ronnie and get justice for him. That day is today."_

The doors to the Pipeline opened up with one touch of a button, and everything that was once the Particle Accelerator came into view. 'Big and empty' were the first words that crossed Caitlin's mind as she stepped inside, glancing around at the cells that had been designed to hold all the meta-humans she captured with her team. Her team. The words echoed in her mind with each step that took her closer to one of the cells reserved specially for someone she never thought would find behind the glass. Barry, Cisco and… Harrison; they had been there with her since the very beginning, when the explosion and lightning had struck, giving these speed abilities to her. Through everything that she faced, Caitlin found that she was never alone and in the past year, after all the ups and downs, dangerous fights and close encounters with all sorts of enemies, she thought that she was prepared for anything else that would come her way, but never once did she imagine herself being so wrong in all her life.

"Caitlin." There it was; the voice of the one man she had trusted beyond a doubt, whom she had defended against everyone else, whom she had loved once… the one who ultimately betrayed her when he revealed his real identity.

"I see you've made your choice." Harrison… no, Eobard Thawne looked down at Caitlin from his cell, hands behind his back, watching her closely.

She chose not to say anything in reply to his statement; there was nothing left between them and if there was a way, Caitlin would have had her memories erased of their time together. Time that was now a lie, a painful, meaningless, _nothing_... that she chose to forget. It wouldn't help her if she remembered the times they had before and after. When they used to flirt shamelessly while working together on the Particle Accelerator, when he would take her out to dinner after eating leftovers in his office several times in a week, when she invited him to her house, when he saved her life the night of the explosion only for him to get paralyzed and her to still get struck by lightning, when she woke up from a 9 month coma to hear from Barry and Cisco that he had stayed beside her the whole time, when he helped her train to become The Flash, when he said that he loved her and she said that she loved him.

"You hold both our futures in your hands now, Cait." He spoke again, knowing all too well that she was ignoring him to the best of her abilities.

"Don't." Her voice was cold when she finally spoke, breaking her resolve to stay disconnected from him until she heard him call her 'Cait' which was too personal; she wasn't about to let his words affect her anymore. " _Don't_ call me that." Caitlin stared at him, her hands curled up into fists by her sides.

Memories were trying to force their way to the surface, much more intimate than ever. Caitlin stood there, unmasked, as she tried to concentrate on the mission at hand; she knew that everyone else was upstairs in the Cortex, listening to everything that was being said between her and Eobard, but they didn't know what she was thinking.

 _"You always did look good in red leather." Harrison smirked when he saw Caitlin in the Flash suit for the first time._

 _"I believe in you Cait, for what that's worth,_ I _know you can do this. Trust yourself." His words were calm and soothing through the earpiece as he helped her take down the first of many meta-humans._

 _"I'm sorry for what happened with the man in the yellow tonight." Harrison said to her as she patched him up, cuts and bruises alike from his fight against the person who had killed her first love and nearly did the same a second time._

She would soon realize that it was nothing more than a speed mirage of this man himself, the man who called himself Harrison Wells, the man she had fought against in the stadium, the Reverse Flash. Caitlin felt herself starting to tremble as she pushed away all the thoughts, realizing a little too late that it was out of anger, for he had seen it too and there was no time for this; the one opportunity she had to go back in time and change the past was limited. She couldn't falter; if she did, then it would mean… that dark and dangerous voice in her head was real, that those words she heard being whispered were true, that despite everything, there was still a part of her which still loved him even now… and Caitlin couldn't let herself believe that.

"I know that you can do it, Caitlin." Eobard said, echoing his words of support just as he had the first time.

Still staying silent, Caitlin simply pulled her mask on and finally tore her gaze away from him as she felt the speed force flowing through her veins, charging up to go faster than she ever had before, the yellow lightning coursing across her body.

"Now run, Caitlin, run." His voice was no more than a soft whisper now, but Caitlin saw the look in his eyes and tried not to smile, a smile that held a secret, one which _nobody_ else knew about.

And so she started off, running around the Accelerator in fast circles, going faster and faster… knowing that she had to reach the speed of Mach 2; within a matter of seconds, before she knew what was happening, Caitlin found herself seeing… visions of her past, her future and glimpses of things that _could be_. Her focus was centered around something very specific though, a time and a place that she hoped she could reach, where no one thought she would think to go. The next thing Caitlin realized was that someone had released the hydrogen particle. It caused a blast of sorts that reverberated throughout S.T.A.R. Labs and in the blink of an eye, she was gone.

* * *

The dark and gloomy road looked deserted, save for an overturned car and two figures just beside the crash when a loud crackling noise surprised them both. There was a wormhole that opened up in the middle of nowhere and out of it came a figure clad in red leather; a mysterious stranger who somersaulted before coming up to stand a few feet away from the two men watching everything happening in confusion.

" _You_!" The blond haired man who was standing over the other person, suddenly realized what was going on.

"Me." Caitlin's voice sounded normal but cold, as she saw the true face of her nemesis and without hesitating, she punched him.

There was enough strength in that punch, combined with her powers to fling the man across the street, where he landed at a safe distance away.

"What... what was that?" The second man, who had been lying on the road suddenly spoke up.

"Harrison!" Caitlin exclaimed as she turned around to face him; he looked shaken and had a cut on his forehead but he was very much alive.

"Who are you? How do you know my name?" Harrison said as he tried to sit up.

"I'm a friend. Look, I can't explain everything now, but your life is in danger... that man is unconscious right now but he won't be for long, I can help you get out of here." Kneeling down to his eye-level, Caitlin tried not to stare as she finally saw the real Harrison Wells in front of her.

"No! Please... my wife, Tess. She's still trapped in the car, I can't leave her behind; she was badly injured." He couldn't see a face behind the mask but he chose to trust this oddly dressed woman because she had saved him from the other stranger.

"Let me." She touched his shoulder, telling him to stay put.

There wasn't much time to waste, Caitlin knew that and rushed over to the car; sure enough, she could see Tess inside but it was impossible for her to tell if the other woman was still alive. A quick glance at where the unconscious form of Eobard Thawne still lay told Caitlin that she had a moment to spare. She used her hands to vibrate the jammed door open and within seconds, reached in to slowly remove Tess from the passenger seat, carrying her over to where Harrison sat as he grabbed a hold of his wife.

"Tess! Tess… can you hear me?" Frantically, Harrison tried to wake her up as he held Tess in his arms, but there was no response.

Caitlin wondered how long it had been since the accident, she couldn't have arrived more than a few minutes after; perhaps there was still a chance to… she bent forward and checked Tess's wrist for a pulse.

"Harrison, I'm sorry…" Caitlin said in a soft voice, knowing what he was going through right now; she could still remember the night that Ronnie died and how painful it had been for her.

"There must be something we can do," Harrison seemed oddly calm, probably he was in shock, as he looked at the masked woman, "A hospital. We can take her to the hospital…" He started to suggest when all of a sudden things changed drastically.

The two of them had been busy trying to help Tess that neither one realized when Eobard had woken up and attacked when Harrison and Caitlin were caught unawares. He slammed straight into Caitlin, throwing her across the street, panting hard as he caught his breath.

"Don't think that just because you're a girl, I won't fight you." Watching as she rolled over on her back before jumping to stand up, Eobard frowned as he studied the woman standing in front of him.

"Good, because I'm not going to make this easy." Caitlin said, shifting into a fighting stance; Barry had trained her to fight with her hands if the time ever came for it and she was prepared.

"Who are you exactly?" Eobard asked as he casually started to have a conversation, not doing anything else yet. "I mean, I know you're the Flash, but you're not the one who chased me back here from 2024." There was something different about the way this one held herself, she was brave as always, but not familiar to him.

"Why don't you tell me, since you're supposed to be a genius and all that?" Taunting him was probably not the best idea, but Caitlin didn't want to make the first move; she may have known one version of this man, but he was still probably as cunning as ever.

"Well well well… looks like someone's a fan," He smirked at her, "I'd say that you are… the Flash from this time. The young girl I saw not more than a month ago, all grown up now." As he answered the question, it hit Eobard what this really meant.

Caitlin could see the realization in his eyes, blue ones that were not like the eyes she had been captivated by; this was a different man, the real Eobard Thawne who had killed Harrison and stolen his face, his name, his life. And yet, she knew that he was also the Reverse Flash, someone who she'd been fighting for centuries if the other him was telling the truth.

"This means that my plan works… I create the Flash! You… you being here proves that." Eobard looked delighted and filled with glee, and all Caitlin wanted to do was punch him in the face again; this man was nothing like the one she knew.

"Not for long, I'm going to make sure that you don't take any more innocent lives Thawne." Caitlin stood her ground, knowing this was a risky situation she was in, but why was he not fighting her?

Hearing the conviction in her voice, Eobard stared at Caitlin with an incredulous look on his face; he seemed… on the verge of laughing?

"Oh my dear, I'd certainly like to see you try." He was still grinning but he knew that she was being serious. "I assume you're here to protect this man's life?" Eobard went on to say, pointing to Harrison who had finally closed Tess's eyes, now looking at Caitlin in wonder.

"His and everyone else that you've killed since tonight and before." She wasn't about to let him forget that he had killed Ronnie as well; for her it may have been ten long years, but to Eobard it was something he wouldn't remember if it happened the previous day.

"Well now, this should be interesting." And then he smiled that sly smile which told Caitlin that he was hiding a secret; it was an eerie echo to the moment she had earlier facing the other him, the one who looked like Harrison, when she had this secret to hide from him and everyone else.

"You have no power here. The speed force was drained from your system, trapping you here in this time. You told me that." Caitlin stated, hoping that her fears weren't about to come true, it wasn't possible… was it?"

"True, that is true." Eobard clearly was taking pleasure in drawing this out, "And yet… all I need to go back to my time is the power of the speed force that begins with you, _Flash_ … and here you are." He made a show of hands, gesturing to her. "To travel a decade in the past means you broke the barrier of time and space, you've harnessed your abilities to its limit… having you here gives me a chance to recharge so to speak."

As he spoke, Caitlin saw that Eobard's words were true; she may not have understood exactly how he was siphoning off the speed force for himself, but there was no mistaking the red lightning that was dancing in sparks over his hands as he showed off.

"Shall we begin?" His voice changed as he vibrated his vocal chords, sounding like the Reverse Flash now.

She knew what Eobard's plan was; to kill Harrison and make sure that he took over his life… but Caitlin remained where she was, between Eobard and Harrison… ready to fight the Reverse Flash once more… she watched him use the gold ring that held his yellow suit, changing into it instantly as he called on the power of the speed force, lightning starting to flow all over his body and his eyes glowing completely red. This time, there was no backup for her, no Firestorm and no Arrow, but Caitlin stood her ground, and suddenly found herself remembering Eobard's words to her from their talk in the Pipeline.

 _"We're enemies, rivals, opposites… reverses of one another… but somewhere along the line, Caitlin, I fell in love with you."_

She wondered if that was really Eobard talking, or if it was possible that some part of Harrison had lived on after he died; because the man standing in front of her now was nothing like the Eobard she once loved. And as she glanced back to meet Harrison's gaze, Caitlin knew that this was not the man she thought she had loved either… but he could have been… perhaps… in another lifetime. When they were still Harrison and Caitlin, moving on from the loss of their loved ones, finding solace in each other, falling in love together, a real and true love that meant something. Despite everything, Caitlin also knew that no matter what happened, she _wasn't_ going to let him die.

"You can't beat me Flash, you never will." Eobard taunted, just as he always had; some things never changed.

"If you want him, you'll have to go through me." She said, sparing one last glance at Harrison, knowing that the situation was much more dangerous now that Eobard had access to the speed force as well.

Caitlin closed her eyes as she pictured the faces of all her loved ones, waiting for her back home at S.T.A.R. Labs - Barry, Cisco, Iris, Felicity, Eddie, Jason and Professor Stein. She was never alone, she hadn't been for a long time, and now she had one more person to fight for… Harrison Wells. Opening her eyes, which were glowing with lightning sparks as her body turned into a blur, she charged forward knowing that he was going to do the same; red and yellow, the Flash versus the Reverse Flash, forever destined to fight each other till their very last breath.

* * *

 **Well? Reviews?**


	2. Author's Note

**A/N: To the guest reviewer, thank you so much for your awesome full caps review! I would love to do more but I really get a bit confused about time travel and all the things that will work and make sense, and also, I kinda personally like that it ends on a cliffhanger where no one knows how things go from that point... the suspense of not knowing y'know? and also, I don't think I figured out what I would have done next... if Caitlin took original!Harrison back to 2015 with her then where would they go from there... Eobard would never be there locked up in the pipeline because he never had Harrison's identity to begin with so would she still be the Flash without him creating the Particle Accelerator? Timey-wimey stuff that I'm not an expert at!**


End file.
